Circular knitting machine and method of operating same



y 8, 19 R H. LAWSON 2248.880 I CIRCULAR KNIT' IING MACHINE AND METHOD OF OPERATING SAME I Filed April 2, 1940 4 Sheets-Sheet} ROBERT H. LAWSON w I 2y has a/Z-Z-arrzeys 37;)

- 7 M M a CIRCULAR R. H. LAWSON I 7'5"? 7/7 7160 m? h KNITTING MACHINE AND METHOD OF OPERATING SAME Filed April 2, 1940 4 Sheets-Shet 2 a 74/ Q 2 74 Q 0 74 [raven/Z07- ROBERT H. LAWSON y 1941- N R. H. LAWSON 2.248.880

CIRCULAR KNITTING MACHINE AND METHOQ 0F OPERATING SAME 4 Sheets-Shet 3 Filed April 2, 19 40 j RUBBER YARN T 'H' SUPPLY 4 RUBBER 110 FEED R 72 I MOTOR THIN THIC K STRAIGHT STRAIGHT WAVY STRETCHED 7 3,; MERCURY MQLTIPLE Y SWITCH 120 72/. iza

,-r 43 x 7.9 739 i 8 Ihve nlar ROBERT H.LAWSON IN POUN'DS y 1941- R. H. LAWSON 2.248380 CIRCULAR KNITTING MACHINE AND METHOD OF PERATI-NG SAME Filed April 2, 1940 4 Sheets-Sheet 4 WEIGHT -.O| LBS.

' I 2 STRETCi I' lR-INCHES 3 INCHES RUBBER I OAD ELO'NGATI'QN T12 5.

fnvenivr Patented July 8,- 1941 UNITED stares PATENT OFFICE cmcmn'n KNIT mrrnon or TING MACHINE AND OPERATING SAME Robert H." Lawson, Pawtucket, R. 1., assignor to Scott & Williams, 1ncorporated, Laconia, N. H., a corporation of Massachusetts Application April 2, 1940, Serial No. 327,495

' g 9 Claims. (Cl. 66132) This invention relates to rubber yarn feeding die cylinder underwear machine embodying this invention; I

Fig. 2 is a plan view, taken on the line' 2-2 of Fig. 1, of the furnishing means which form part of the rubber feeding means;

.Fig. 3 is a view in side elevation, broken away on the line 3-3 of Fig. 1, of the positive feeding meansfor erubber yarn;

Fig. 4is a viw in perspective of the contact tension on bare rubber yarn may not produce uniform stretch. One reason is imperfection in the tensioning mechanism, and, another, variation in the yarn. It is almost impossible to feed bare rubber yarn under substantial uniform tension because bare rubber has a high coefficient of friction and tends to catch on anything against which it rubs. If such a yarn is dusted to reduce the friction, this dusting" is sure to be slightly irregular and there will be trouble if a disk tension mechanismis used to give the tensioning. With certain other types of tensioning mechanism there is a tendency for the parts to bounce, thus producing irregularity.

Variations .in the yarn may be of many different kinds. Rubber yarn always has inequalities in size, and any variation in size will give a considerable difference in stretch under uniform plate of the multi-point mercury switch for con-' trolling the yarn furnishing means of Fig. 2

Fig. 5 is a diagrammatic view of the condition of the rubber yarn at the various points as it passes through the machine, suflicient of the associated electrical and mechanical elements being shown to make the changes in its condition intelligible;

' Fig. 6 is astretch-tension graph of a typical rubber yarn suitable for use in the machine of Figs. 1 to 5, showing while Fig. 'Tis a graph on an enlarged scale of the low tension end of a graph test on a similar yarn. The great difficulty in using rubber yarn in circular knitting machinery where yarn is fed in under tension is the elastic nature of-the yarn. This is particularly true in the case of bare rubber, where the amount of stretch is greater than with covered rubber yarn and where surface friction problems arise between the rubbar and anything against which it rubs. Many efforts have been made to eliminate the nonthe main part of the curve;

uniformity and they have been based on the theorythat the way to achieve this end is to feed the yarn under uniform tension. I have discovered that uniformity in the finished garment is best. obtained by feeding the bare rubber yarn under uniform stretch, and I have devised mechanism which feeds the yarn under uniform stretch.

'llhere ate a number of reasonswhy uniform yarns.

tension. Again the composition of the rubber may vary and result in variation in stretch when applying uniform tension. In fact yams of the same diameter but with different compositions are, made especially to have different capacities to stretch under the same amount of tension. Thus certain yarns are known as long stretch The applicant has noticed another important fact with regard to stretching bare rubwhere a little difference in tension causes a large change in length of the yarn.-.

All these considerations show that it is impossible to expect bare rubber yarn to be incorporated in weft knitted fabric in a uniform manner if the rubber yarn feeding-as distinguished from the feeding of the ordinary yam-is based on supplying the bare rubber yam under uniply and deliver it in a slack loop, thereafter taking the rubber from this free loop on a surface inate this waviness without of the arm. The eye which travels at a slower linear speed than the speed at whichthe yarn is being knitted. The rubber yarn comes to this surface in a substantially unstretched condition and straight line, by virtue of my mechanism. The uniform stretch thus imparted is maintained to the needles.

My mechanism comprises several elements which cooperate in a knitting machine to give a high grade commercial product in which bare rubber is knitted while stretched uniformly. First, there is a supply or source I of rubber yarn. as for instance, a spool of bare rubber yarn. Next comes a yarn furnishing means, that is to say, means which will pull the yarn from the spool and present or furnish it constantly free of all tension and stretch, in adequate quantity for the knitting. I The most convenient way to keep this unstretched yarn is in a loop. After the furnishing means come a floating or feeler arm and a positive yarn stretching device. The stretching device delivers the rubber yarn at a rate slower than the knitting, thus causing stretch. The interrelation between the furnishing means, the feeler arm and the positive stretching device is important and will be described in detail.

Attention should first be called to the fact that rubber yarn, if hanging free in a loop and subjected only to its own weight, is generally of a wavy character, i. e., has a stillness or "set which causes the rubber to assume various waved shapes. This results in increased and irregular feeding or stretching of the yarn as it passes through stretching means. One function of the feeler arm element of the combination is to elimintroducing stretch into the yarn. The free end of the feeler arm is hooked or hung on the loop of rubber yarn between the furnishing and the stretching means. For this purpose there is an eye I30 in the end I30 is preferably nearly under the stretching device, and the movements and arrangements are such that only the rubber between the eye and the stretching means is straightened. The yarn being presented to the stretching device in a tensed but unstretched condition, and the latter driven in timed relation to the knitting elements, it therefore follows that the rubber yarn is fed to the needles with uniform stretch. The feeler arm functions as a control and it has so little inertia and is so balanced that it floats on the rubber without exerting. stretching tension on the yarn going to the positive stretching device. It electrically controls the speed of the furnishing means so as to keep a sufficient length of loop of yarn between the furnishing means and the stretching device at all times.

' Referring now to the drawings, the invention is shown and will be describedembodied in a Scott 81 Williams revolving needle cylinder underwear machine with a, multiplicity of feeds, but only sufficient of the machine will be described to make plain the manner in which the rubber yarn is fed and controlled. The machine has a base I0 in which is supported a revolving needle cylinder and revolving dial carrying independent cylinder needles 25 and dial needles respectively, the knitted fabric I50 passing downwardly through the center of the machine through drawing rolls into a can, in the usual manner. The .dial 30 is carried by a central dial post 3| from a dial bracket 32 held on supports 33. These supports are mounted in the base I0 of the machine and extend upwardly through the central post 3| is a shaft (not shown) for driving the dial, the shaft being turned by device being positively i a dial driving gear 36 mounted above the dial bracket. The dial driving gear can be driven by pinions and shafts from the same gear ring which drives the needle cylinder. A guard 40 surrounds the dial driving gear 36.

Thereis an original supply I00 of bare rubber yam R mounted on a yarn spool bracket 50 on the upper ends of the supports 33, some little distance above the guard. From the spool I00 the rubber yarn R is drawn by a yarn furnishing means. This furnishing means consists of a small, motor-driven device for drawing or pulling the bare rubber from the supply at a rate varied in accordance with the demands of the knitting machine. The device includes a small electric motor IIII mounted on a plate IiI adjacent the periphery of the guard 40 by means of an arm II2 associated with the dial bracket 32. The motor has two yarn advancing spindles H5, H6, arranged parallel to each other in spaced relation in a horizontal plane'and both are driven in a clockwise direction as viewed in- Fig. l, by means of small gear wheels II! which mesh with a small gear wheel II8 on the end of the shaft of the electric motor H0. Each of the spindles H5, H6 has a plurality of circumferential grooves II9 which can best be seen in Fig. 2. The rubber yarn is wrapped around the spindles in large open loops, each embracing both spindles. The yarn progresses from one groove Hi! .to the next in succession and from the motor end of the spindles toward the outer or free ends where the yarn drops oil by gravity. It will be obvious that the rotation of these spindles under the drive of the motor will cause the yarn to be drawn from the yarn supply I00 and released in a free or unstretched condition at the outer end of the two spindles.

From the furnishing means the yarn proceeds downwardly and laterally to the outer end of a ieeler or control arm I20 which is pivotally carried as an extension of an operating contact plate I2I of a multiple contact mercury switch I25. This mercury switch is carried on a bracket I26 supported from the plate III which carries the electric motor IIO. For adjustability the bracket I26 has a vertical rod I2I interposed between it and the plate III. This mercury switch I25 is adapted to control the operation of the electric motor IIO by means shown diagrammatically in Fig. 5. The switch has a plurality of points I22 carried by a contact plate I2I shown in Fig. 4. This multiplicity of points is' so located with regard to the mercury I23 in the lower portion of the switch that as the circular contact plate I2I is rotated the number of points which are in contact with the mercury is varied. From each contact point there is a wire I24 running to a different point on a resistor I28. The amount of current which flows through the circuit formed by the mercury contacts, the resistor and the remainder of the electrical circuit varies with the changes in the number of contact points in the mercury. The resistor I28 is electrically connected to one side of the electric motor H0 operating the spindles H5 and 6 which draw the rubber yarn from the supply I00. The other side of the circuit to the electric motor .is connected to the source of current and back to the mercury through various auxiliary devices which swinging the points into and out of the mercury in succession, the plate receiving its rotarymovement' from a cylindrical casing I32 which encloses the trough containing the mercury. This casing is fast on the contact plate and is adapt: ed to rotate on its longitudinal axis with that plate. Encircl-ing the casing at its middle is a strap I3I which carries the feeler arm [20 previously referred to. The angle of the feeler arm with relation to the points in the contact plate can be adjusted by loosening the strap I3I on the casing I32, turning it with relation to the casing and tightening it again. The relation of the points and the feeler arm is such that when the feeler arm is raised, the number of points in contact with the mercury is increased. The electrical circuit including the motor. is such that when the inertia arm is raised the speed of the motor is increased progressively.

From 'the eye I30 in the end of the arm the rubber yarn passes upwardly to a positive feeding mechanism comprising the positively driven bevelled or conical wheel I with a, pressure roll IdI squeezing the yarn against the 'wheel I40. There are guide rollers I42 and 3 respectively located in leading and following posifrom the positive feeding means substantially without stretching the yarn. Stated another way,

the weight of the feeler arm can be said to beof the order of the unstretched pull of the'rubber yarn. Since the weight of the arm will straighten but not stretch the rubber to any appreciable tions with regard to pressure roller IQI, and the rubber yarn passing over these guide rollers is led between the feed roll 0 and the pressure roll MI. The feed roll H0 is positively driven from the dial driving gear 38 by means of a small gear I41 engaging the periphery of the dial driving gear 36 and in turn driving two bevel gears I06 carried by a bracket I68 on the support 33 above the dial driving gear '85. The bevel gears I 66 acting through a clutch 605 and which v along with the conical feed wheel M0 are sup-.

ported by abar bracket 9 on the bracket I, drive the feed wheel I00 so that it is positively driven with relation to the needles. The gearing relation is such that the linear speed of the yarn passing between feed wheel M0 and the pressure roll MI is less than the amount of yarn drawn by the needles and may be less than the peripheral speed of the needle cylinder 20, which results in stretch being given to the rubber yarn. It will be seen that by this positive driving arrangement of the wheel M0, a uniform amount of the rubber yarn as presented to the wheel I40 will be fed to the needles and the yarn will be stretched uniformly. The conical shape of the feed wheel I 50 permits variation of the stretch to shape the garment.

As already explained. the rubber yarn R coming off the spindles H5, lid of the rubber furnishing mechanism is completely relaxed and free of tension and stretch. It generally takes a "set and therefore is in a somewhat wavy condition when it leaves the spindles H5, M6 for the eye I30 in the end of the feeler arm. .From the feeler arm the'rubber goes upwardly to the positive feeding means I50, MI. The weight of the feeler arm is so slight and it is so freely mounted that it will straighten this length of rubber between the eye in the end of the arm and the positive feeding means, but will not stretch it to any appreciable extent. In other words. the pull of gravity on the feeler rm is such that the arm can be lifted by an upward pull on the rubber yarn .after, as the needles are drawn extent it follows that the rubber comes to the feed roll 0 in astraight but unstretched condition,

and being thus presented to the feed wheel in an absolutely uniform manner, it is stretched a uniform amount as it leaves the feedwhe'el. One example of a feeler arm has weight'such'that gravity exerts a pull of say .002 lb Part of this pull being taken by the rubber between the furnishing means and the eye I30, the pull on the rubber going to the feeding means is'lessthen i .002 1b. I find that-with #50 rubber it takes about .0025 lb. to start the yarn stretchingh lt should be pointed out that inFig. 1 the waviness of therubber between the wheel IIBand the eye I30 is exaggerated. The angle between this portion of the rubber and the portion leading from the eye to the feeding means need not be constant in all construction, and the angle of each portion from the vertical may also be varied, so long asthe pull of the arm on the rubber to the feeding means is less than the maximum pull for zero stretch. The existence of this maximum pull zero stretch point is shown in-Fig. 7, where it will be observed thatincrease' in tension does not result in stretch until the puil goes above approximately .0025 lb.- (The, vertical scale of Fig. I is ten times larger than'that of Fig. 6.) This figure was the result of a test of size 50 elastic yarn. The figure would vary somewhat with yarns of other sizes. I

In order that the uniformity may not be lost before the yarn reaches the needles, it is preferable to provide means at every point where the rubber yarn has to turn through any substantial angle to avoid frictional or sliding resistance to the yarn. Also friction on stretched bare rubber chafes and weakens it. Thus Where the yarn' turns to go through the yarn finger its, a roller I35 is provided which avoids any sliding'contact with the yarn in turning that angle. This roller I35 is carried by a support I3? mounted on the outer surface of the stationary cam cylinder I6. If desired, stop motions I 33 and 53d operated on an electrical circuit can be provided between the rubber yarn supply Hi0 and the spindles H5, N0 of the yarn furnishing means and betwen the positive feed wheel I00 and the roller I35 respectively. These are adapted to stop the knitting machine and themotor 0 any time the rubber yarn breaks.

In the lower right hand corner of Fig. 5 hasand sinkers 26 moving from left to right in the direction of the horizontal arrow as they'pass the knocking-over point which is indicated by the downwardly pointing arrow. When knitting with bare rubber, the yarn does not rob from one loop to another, and as soon as the yarn has been contacted by the sinkers'ifi and the needles 25, the bare rubber yarn cannot "creep." There I down to knock over the loops, each loop of rubber must stretch still further without any compensation from its neighbors. I! the stretch of the yarn is irregular, "break-outs will then occur at this point. This serves to illustrate the importance of uniform stretch of the rubber: when lsnittingwith bare rubber. Precautions must be taken to see that the stitch is pulled away from the needle. To achieve this a cam, horn or. presser I39 may be provided, carried by a bracket I38 on the main frame III of the machine. tends from the outside of the frame underneath the cam and needle cylinders, holding the presser or cam I39 itself inside of the needle cylinder but outside of the fabric I50 as it extends downwardly toward the regular fabric takeup I5I and the can in which the fabric is being collected. This cam I 39 is directed radially inward and exerts extra pressure against the fabric 'opposite the knocking-over point and for a short distance on either side thereof. This extra pressure exerted by cam I39 is'accomplished by concentrating at this point more of the tension from the regular fabric take-up I5I, than would be normal were 2. In a method of feeding rubber yarn to the The bracket I38 exthis cam not present. In this, way it cooperates with the regular knitting elements and the takeup in taking the stitches from the needles and completing the knocking-over operation. It might be noted that the knocking-over referred to is the knocking of the inelastic yarn over the rubber yarn. It also assists in preventing the stitches or loops left on the needles from following the needles'out as they are raised following the knocking-over point.

The rubber yarn may be fed at any number of feeds desired, and if preferred, inelastic yarn can also be fed at the feeds where rubber is present, as indicated for instance by the dotted inelastic yarns C and C' in Fig. 1. It has heretofore often been thought-necessary to feed inelastic yarn in with the rubber so that if the rubber does break there will be no runs in the fabric. However, owing to the accurate control of the stretch of the rubber in accordance with this invention, the rubber stitches will not break out and the inelastic thread knit with it can be eliminated. The new means operates so accurately as to permit shaping of the garments by varying the stretch given the rubber by the cone wheel I40. This results in a cleaner fabric due to the absence of this extra thread, which tends ot make pile loops and also makes a greater narrowing of the fabric possible. The elimination of the thread also saves the cost of the extra' yarn. Whether inelastic yarn is fed in with the rubber yarn or only at other feeds, inelastic yarn loops lie on both sides of the fabric and cover the rubber yarn, thus preventing the rubber yarn from coming into contact with the wearer. Still another advantage of the use of bare rubber-when fed in accordance with the present invention is the possibility of spacing the rubber yarn further apart in the fabric than is practical with covered rubber.

While the invention has been shown and described in connection with bare rubber,-and it is peculiarly usefulfor that purpose-the invention may in certain cases be useful for the feeding of covered rubber.

It will be obvious that many modifications which do not depart from the scope of my invention will occur to those skilled in the art.

What I claim is: g

1. In a circular knitting machine, rubber feeding means comprising a yarn supply, means taking yarn from the supply and furnishing same free of tension, in combination with a feeler arm whose weight will straighten but not stretch the rubber, said arm controlling the operation of the furnishing means, and a positive yarn feeding means adapted to take yarn from the feeler arm and feed it to the needles under uniform stretch.

needles of a circular knitting machine in uniformly stretched condition by the use of a positive yarn feeding means, the steps of obtaining the rubber from the supply, allowing it to lie free and unstretched and then holding it tensed but without stretch by means of a gravity pull less than the zero stretch maximum pull, as it goes into the feeding means.

3. In a method of feeding bare rubber yarn to the needles of a circular knitting machine by the use of a positive feeding means adapted to put stretch into the yarn, the steps of allowing the rubber to lie free and unstretched as it goes into the feeding means while holding it straight by means of a feeler element, and obtaining the necessary rubber in its unstretched condition from yam furnishing means controlled by the said feeler element.

4. In a method of feeding rubber yarn to the needles of a circular knitting machine by the use of a positive feeding means, the steps of pulling the rubber from the supply, allowing it to hang free but applying suflicient weight as it goes into the feeding without stretching it.

5. In a circular knitting machine, rubber yarn feeding means comprising means adapted to furnish yarn in unstretched condition, and a positive yarn feeding means taking the yarn from the furnishing means and feeding it to the needles under uniform stretch, in combination with a feeler arm whose weight hangs on the yarn entering the positive feeding means with a gravity pull of the order of the unstretched pull of the yarn, said feeler arm being adapted to cause operation of the yarn furnishing means to provide a free loop of yarn between the furnishing means and the feeding means.

6. In a circular knitting machine, yarn feeding means comprising a rubber. yarn supply, means taking yarn from the supply and furnishing same free of tension, positive yarn feeding means receiving yarn from the furnishing means. in combination with means-located between the furnishing and feeding means adapted to provide a free loop of yarn therebetween, said means comprising a feeler arm hanging on the yarn going to the feeding means with a weight sufllcient to straighten but not stretch the rubber, said feeler arm controlling the operation of the furnishing means to maintain a slack loop between the furnishing and feeding means. i

'7. In a circular knitting machine, yarn feeding means comprising a bare rubber yarn supply, means taking yarn from the supply and furnishing same free of stretch, in combination with two stretching devices and a fabric takeup to incorporate the rubber yarn in the fabric in uniform stretched condition, the first stretching device comprising positive yarn feeding means taking the yarn from the furnishing means and feeding same to the needles with uniform stretch, the fabric takeup pulling on the fabric coming from the needles, and said second stretching means comprising a device bearing against the ing means comprising a bare rubber yarn supv nishing same free of stretch,

fabric locally near the knocking-over point and cooperating with the fabric takeup to insure knocking-over of the rubber stitch.

8. In a circular knitting machine, yarn feedply, means taking yarn from the supply and furin combination with a stretching device for said yarn, a fabric take-up and means for concentrating the fabric means to hold it straight take-up to put more tension than the take-up would normally apply ator near the knocking-' over point to insure casting on of the rubber stitch.

9. In a circular knitting machine, yarn feeding means comprising a bare rubber yarn supply,

means taking the yarn from the supply and turnishing same free 01' stretch, in combination with a stretching device comprising positive yarn feeding means to take the yarn from the furnishing means and to feed same to the needles in uniform stretched condition, together with means for applying extra tension on the fabric in the neighborhood of the knocking over pointwhere the rubber stitch is cast oil, to insure knocking over of the rubber stitch.

' ROBERT H. LAWSON. 

